diff options
Diffstat (limited to 'contrib/gcc/config/i386/crtfastmath.c')
| -rw-r--r-- | contrib/gcc/config/i386/crtfastmath.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/contrib/gcc/config/i386/crtfastmath.c b/contrib/gcc/config/i386/crtfastmath.c new file mode 100644 index 0000000000000..5991442686ab7 --- /dev/null +++ b/contrib/gcc/config/i386/crtfastmath.c @@ -0,0 +1,116 @@ +/* + * Copyright (C) 2005 Free Software Foundation, Inc. + * + * This file is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2, or (at your option) any + * later version. + * + * In addition to the permissions in the GNU General Public License, the + * Free Software Foundation gives you unlimited permission to link the + * compiled version of this file with other programs, and to distribute + * those programs without any restriction coming from the use of this + * file. (The General Public License restrictions do apply in other + * respects; for example, they cover modification of the file, and + * distribution when not linked into another program.) + * + * This file is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; see the file COPYING. If not, write to + * the Free Software Foundation, 51 Franklin Street, Fifth Floor, + * Boston, MA 02110-1301, USA. + * + * As a special exception, if you link this library with files + * compiled with GCC to produce an executable, this does not cause + * the resulting executable to be covered by the GNU General Public License. + * This exception does not however invalidate any other reasons why + * the executable file might be covered by the GNU General Public License. + */ + +#define MXCSR_DAZ (1 << 6) /* Enable denormals are zero mode */ +#define MXCSR_FTZ (1 << 15) /* Enable flush to zero mode */ + +#define FXSAVE (1 << 24) +#define SSE (1 << 25) + +static void __attribute__((constructor)) +#ifndef __x86_64__ +/* The i386 ABI only requires 4-byte stack alignment, so this is necessary + to make sure the fxsave struct gets correct alignment. + See PR27537 and PR28621. */ +__attribute__ ((force_align_arg_pointer)) +#endif +set_fast_math (void) +{ +#ifndef __x86_64__ + /* All 64-bit targets have SSE and DAZ; only check them explicitly + for 32-bit ones. */ + unsigned int eax, ebx, ecx, edx; + + /* See if we can use cpuid. */ + asm volatile ("pushfl; pushfl; popl %0; movl %0,%1; xorl %2,%0;" + "pushl %0; popfl; pushfl; popl %0; popfl" + : "=&r" (eax), "=&r" (ebx) + : "i" (0x00200000)); + + if (((eax ^ ebx) & 0x00200000) == 0) + return; + + /* Check the highest input value for eax. */ + asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1" + : "=a" (eax), "=r" (ebx), "=c" (ecx), "=d" (edx) + : "0" (0)); + + if (eax == 0) + return; + + asm volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1" + : "=a" (eax), "=r" (ebx), "=c" (ecx), "=d" (edx) + : "0" (1)); + + if (edx & SSE) + { + unsigned int mxcsr = __builtin_ia32_stmxcsr (); + + mxcsr |= MXCSR_FTZ; + + if (edx & FXSAVE) + { + /* Check if DAZ is available. */ + struct + { + unsigned short int cwd; + unsigned short int swd; + unsigned short int twd; + unsigned short int fop; + long int fip; + long int fcs; + long int foo; + long int fos; + long int mxcsr; + long int mxcsr_mask; + long int st_space[32]; + long int xmm_space[32]; + long int padding[56]; + } __attribute__ ((aligned (16))) fxsave; + + __builtin_memset (&fxsave, 0, sizeof (fxsave)); + + asm volatile ("fxsave %0" : "=m" (fxsave) : "m" (fxsave)); + + if (fxsave.mxcsr_mask & MXCSR_DAZ) + mxcsr |= MXCSR_DAZ; + } + + __builtin_ia32_ldmxcsr (mxcsr); + } +#else + unsigned int mxcsr = __builtin_ia32_stmxcsr (); + mxcsr |= MXCSR_DAZ | MXCSR_FTZ; + __builtin_ia32_ldmxcsr (mxcsr); +#endif +} |